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Electronic viscometer

  • US 5,710,374 A
  • Filed: 06/25/1996
  • Issued: 01/20/1998
  • Est. Priority Date: 04/06/1995
  • Status: Expired due to Fees
First Claim
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1. An electronic viscometer, comprising:

  • a piezoelectric crystal attached to a first side of a metal plate;

    a hollow circular tube having a first end attached to a second side of said plate, said tube having a longitudinal axis perpendicular to said second side;

    said piezoelectric crystal being driven by a piezoelectric drive means having a feedback electrode for providing a feedback signal, wherein said piezoelectric drive means includes a phase compensation network receiving a feedback signal from said feedback electrode and providing a compensated feedback signal to a phase locked loop and wherein said phase locked loop provides a piezoelectric drive signal having the same frequency as a frequency of said phase compensated feedback signal and wherein said piezoelectric crystal receives said piezoelectric drive signal as an input signal and outputs an exclusive longitudinal vibratory motion at resonance to said tube, said tube having at least a second end which has a sufficiently thin wall to maximize shear forces produced by said exclusive longitudinal vibratory motion when said second end is inserted in a liquid whose viscosity is to be measured and wherein said tube has an aspect ratio chosen so that said tube provides said exclusive longitudinal vibratory motion when said piezoelectric drive signal is an oscillating constant root means square value driving voltage.

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